34 lines
873 B
C
34 lines
873 B
C
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/in.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_endian.h>
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SEC("xdp")
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int isTCP( struct xdp_md *ctx ) {
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void *data_end = (void *)(long) ctx->data_end;
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void *data_begin = (void *)(long) ctx->data;
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struct ethhdr* eth = data_begin;
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// Check packet's size
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if(eth + 1 > data_end)
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return XDP_PASS;
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// Check if Ethernet frame has IPv4 packet
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if (eth->h_proto == bpf_htons( ETH_P_IP )) {
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struct iphdr *ipv4 = (struct iphdr *)( ((void*)eth) + ETH_HLEN );
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if(ipv4 + 1 > data_end)
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return XDP_PASS;
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// Check if IPv4 packet contains a TCP segment
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if (ipv4->protocol == IPPROTO_TCP)
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return XDP_PASS;
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}
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return XDP_DROP;
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}
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char LICENSE[] SEC("license") = "GPL";
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